Electric Cars

As a power source for cars, electric energy holds enormous promise. The enthusiastic support of central and local governments around the world for this major element of a low-carbon economy reflects the potential of electric automotive technology as a means of curbing greenhouse gas emissions. Not only are electric cars clean, however, they are also extremely cost-effective to run. The limited number of electric cars actually in production at present cost between one and two pence per mile to run. The attraction of releasing the automotive industry from its dependence on oil is totally seductive.

Electric cars use electric motors and motor controllers for propulsion: there is no internal combustion engine. Instead, power derives from on-board rechargeable battery packs which store electrical energy. The batteries are topped-up by regenerative braking. This process captures the kinetic energy, or momentum, which is generated when the driver takes his foot off the accelerator and coasts, or when the driver applies the brakes. The motor converts the energy to electricity which is stored in the battery. Regenerative braking reduces fuel consumption by about 20%. Electric cars not only do away with the engine block, they also have no gearbox or clutch, so many items included in the regular servicing and maintenance of a conventional vehicle are no longer necessary.

Plug-in hybrid electric vehicles (PHEVs)

Plug-in hybrid electric vehicles, (PHEVs), are normally classified as electric cars. They will qualify for the UK government’s subsidy of up to £5000 when PHEVs and all-electric cars come on stream in 2011.

PHEVs are petrol-electric hybrids with a battery that can be recharged from the mains supply as well as by their internal combustion engine. The major car manufacturers have PHEVs at various stages in their product planning cycles – the Chevrolet Volt from GM is a plug-in series hybrid due to be released in the US in November 2010. Toyota is currently trialling its plug-in parallel hybrid Prius in EDF Energy’s company car fleet in the UK and is leasing 150 models to selected fleets across Europe. PHEVs run on the electric motor for up to 40 miles and then revert to the petrol engine when the battery is almost depleted. (The Volt’s system is different: its petrol engine does not recharge the batteries. When the engine kicks in, it provides energy direct to the electric motor via a 53 kW generator.)  PHEVs are intended for commuters whose daily journeys are within the range of electric-only operation. The batteries are then recharged overnight at home.

The batteries for both all-electric cars and PHEVs are recharged by plugging into a normal 240V 13 amp mains supply – a relatively simple matter for motorists with their own garages but, in the absence of multiple kerbside charging points, a considerably more difficult problem for those who park in the street. To achieve the full potential of this energy source requires the development of an infrastructure which is as yet in its infancy. In December 2009, there were 273 recharging points in the UK, of which 219 were in London – and the vast majority of those were in the borough of Westminster.

Battery technology for electric cars

Fulfilling the promise of electric cars is heavily dependent on breakthroughs in battery technology. Nickel metal-hydride and lithium-ion batteries represent major advances in efficiency and range over lead-acid batteries but they are only steps along the path towards small, light, efficient and cost-effective units. At today’s state-of-the-art technology, lithium-ion batteries for volume-produced electric cars will still require charging over a period of some eight hours, their range will still be limited and their cost makes pure electric cars significantly more expensive than comparable petrol-engined cars. Added to which, they are heavy and have relatively low energy densities.

The Nissan Leaf, for example, due to launch in the US and Japan in late 2010 (Europe in 2012) on a platform of ‘the world’s first affordable five-seater electric car’, takes eight hours to charge from a domestic supply but has a fast-charge capability of an 80% charge in less than 30 minutes. Fast-charging, however, requires a dedicated charger costing $45,000! It’s beyond the budget of the average motorist but Nissan are hoping that filling stations will make the investment. The Leaf’s range is 100 miles on one charge, which Nissan says satisfies the daily driving requirements of more than 70% of the world’s motorists. Its top speed of 87 mph also fits the profile of a majority of drivers around the world.

California-based Tesla Motors have adopted a different strategy for their ground-breaking second model, the Model S. It will have three battery pack options with ranges of 160, 230 or 300 miles per charge. Launching in the US in late 2011 (UK 2012), the car is being marketed as ‘the only car you’ll ever need’.

Renault have announced that there will be potentially three ways to recharge its planned range of four electric cars. Firstly at home, overnight, taking from four to eight hours. Secondly, by taking the car to a rapid recharge station where recharges could take 20 to 30 minutes. Thirdly, an option unique (so far) to Renault, by taking the car to a battery exchange terminal where a machine will remove the depleted battery and insert a fully charged replacement in three minutes. The Renault-Nissan Alliance is in partnership with California-based Better Place, a company that develops grid infrastructures on the battery exchange principle. The first locations where these terminals are being developed on a national scale are Israel and Denmark. The Alliance is in partnership with Better Place to supply electric cars starting in 2011 and planned to reach 100,000 by 2016.

Buying the electric car but not the battery

Although electric cars are more expensive than their internal combustion engine counterparts, there is one way of reducing the sticker price: sell the car but not the battery. Ownership of the battery would remain with the manufacturer or dealer while the customer only leases it. In this way, battery leasing becomes a running cost like servicing. India-based REVA, the company that makes Britain’s best-selling electric car, the G-Wiz, has announced indicative prices for the company’s two new advanced models commencing production in 2010 and 2011 respectively. The prices quoted exclude lithium-ion batteries – the price for these is included in a monthly ‘mobility fee’.

Nissan also intends to lease batteries for a monthly charge which makes a very significant difference to the Leaf’s sticker price. With the battery, the price of the car is £18,000-£20,000 but take away the up-front price of the battery and you’ve lowered the price by £6,000.

Peak torque at zero rpm

An internal combustion engine has very little torque at low rpm and only reaches peak torque in a narrow rpm range. This necessitates frequent gear changes to maintain optimal torque. The opposite is true of an electric motor: all electric cars develop their highest torque from zero rpm. As there is no clutch to contend with and with the availability of maximum torque immediately the driver presses the pedal, acceleration is vivid and stays responsive all the way to maximum rpm.

Tesla Motors’ first model, the Roadster - an all-electric two seater sports car - went on sale in the UK in mid 2009. It has a 0-60 mph time of 3.9 seconds and, to quote Tesla, ‘delivers giddy acceleration with a redline at 14,000 rpm’. The top speed is limited electronically to 125 mph. The battery pack consists of several thousand consumer-grade lithium-ion cells providing the car with a range of 244 miles. But this performance, and the efficiency that comes with it, does have a price tag of £100,000 plus.

The Lightning GT, the first product from the UK-based Lightning Car Company has an electric motor fitted into each wheel providing motor and drive electronics. Its Altairnano lithium-titanate battery pack offers ultra-fast charging in only ten minutes. This combination gives the Lightning GT 700 bhp with a 0-60 mph time of 4.0 seconds and a top speed limited to 130 mph, together with a range of 200 miles on a single charge. The car will be trialled as part of a consortium taking part in the Technology Strategy Board’s Demonstrator project in 2010.

All-electric cars versus PHEVs

Amongst the car manufacturers there are significant differences in the direction they are taking over the next decade. Renault surprised the industry by introducing their range of four all-electric vehicles at the 2009 Frankfurt Motor Show. Although they were labelled ‘concepts’, it was an open secret that they are very close to the cars that will be launched in 2011/2012. Renault and its alliance partner Nissan are investing 200 million euros a year in a bid to carve out a sizeable share of a global market that CEO Carlos Ghosn forecasts will represent 10% of car sales by 2020 and between 15% and 25% in Europe due to government subsidies. The Alliance is also investing heavily in batteries for electric cars: the plan is to produce 100,000 batteries a year from mid 2012 with an investment value for the first phase of the project estimated at 600 million euros.

So Carlos Ghosn has committed his company firmly to an all-electric product future. But Toyota takes a very different view. It has gone on record as saying that ‘the conventional petrol-hybrid, like the all-new Prius PHEV, is considered Toyota’s long-term core powertrain technology.’ The only roles Toyota foresees for pure electric cars are as small city cars and as commercial vehicles. Both suit daily driving routines that are predictable and limited in their range. Hence Toyota is progressing with its small, low-powered, all-electric city concept car that it showed at the Tokyo Motor Show in October 2009.

‘No break-throughs in either batteries or infrastructure’

Toyota doesn’t see any short-term break-throughs in battery technology on the scale necessary to power volume-manufactured family-sized cars, and the obstacles to reducing the size and weight of today’s lithium-ion batteries appear insurmountable.

The company is similarly doubtful about the massive financial investment necessary to create a viable infrastructure. Quick charging points, they say, will cost in the region of £30,000 each and no-one has yet come up with an answer to the questions as to how to you provide sufficient charging points to service people who have to park in the street or who live in blocks of high-rise flats.

The internal combustion engine?

Over the next decade we will also see the development of an infrastructure for electric cars like the Renault range, the Nissan Leaf and the Toyota Prius plug-in hybrid, and hydrogen fuel cell cars like the Honda FCX Clarity. The degree to which that infrastructure grows depends to a large extent on the political will of governments and international bodies including the EU, G-20 and the UN. They will be driven by the twin objectives avoiding dependence on imported oil with its fluctuating price, and the transference to low-carbon economies. They are therefore likely to encourage the development of an infrastructure as electric and hybrid cars, followed by fuel cell cars, become more common towards 2020. The differing strategies of Renault-Nissan and Toyota will be good for consumer choice and probably for car pricing as well.

To quote The Economist ‘‘... propelling modern transport by means of serial explosions in an array of tin cans does seem an incredibly primitive way of doing things. The time is ripe for a change.’